U.S. patent application number 11/180841 was filed with the patent office on 2006-01-26 for nano and mems power sources and methods thereof.
This patent application is currently assigned to ROCHESTER INSTITUTE OF TECHNOLOGY. Invention is credited to Ryne P. Raffaelle, David Wilt.
Application Number | 20060017108 11/180841 |
Document ID | / |
Family ID | 35656239 |
Filed Date | 2006-01-26 |
United States Patent
Application |
20060017108 |
Kind Code |
A1 |
Raffaelle; Ryne P. ; et
al. |
January 26, 2006 |
Nano and MEMS power sources and methods thereof
Abstract
A power source and methods thereof includes a structure
comprising one or more p type layers, one or more n type layers,
and one or more intrinsic layers and at least one source of
radiation is disposed on at least a portion of the structure. Each
of the p type layers is separated from each of the n type layers by
one of the intrinsic layers.
Inventors: |
Raffaelle; Ryne P.; (Honeoye
Falls, NY) ; Wilt; David; (Bay Village, OH) |
Correspondence
Address: |
Gunnar G. Leinberg, Esq.;Nixon Peabody LLP
Clinton Square
P.O. Box 31051
Rochester
NY
14603-1051
US
|
Assignee: |
ROCHESTER INSTITUTE OF
TECHNOLOGY
Rochester
NY
GLENN RESEARCH CENTER
Cleveland
OH
|
Family ID: |
35656239 |
Appl. No.: |
11/180841 |
Filed: |
July 13, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60587364 |
Jul 13, 2004 |
|
|
|
Current U.S.
Class: |
257/353 |
Current CPC
Class: |
G21G 4/00 20130101; G21H
1/04 20130101 |
Class at
Publication: |
257/353 |
International
Class: |
H01L 27/12 20060101
H01L027/12 |
Claims
1. A power source comprising: a structure comprising one or more p
type layers, one or more n type layers, and one or more intrinsic
layers, wherein each of the p type layers is separated from each of
the n type layers by one of the intrinsic layers; and at least one
source of radiation is disposed on at least a portion of the
structure.
2. The power source as set forth in claim 1 wherein the at least
one source of radiation is at least one of an alpha particle
emitter and a beta particle emitter.
3. The power source as set forth in claim 1 further comprising: at
least one hole extending at least partially into the structure; and
a first conductive contact disposed on the inner surface of the
hole.
4. The power source as set forth in claim 3 wherein the at least
one hole extends substantially through the structure.
5. The power source as set forth in claim 3 further comprising:
another hole extending at least partially into the structure; and a
second conductive contact disposed on the inner surface of the
another hole.
6. The power source as set forth in claim 5 wherein the at least
one hole and the another hole each extend substantially through the
structure.
7. The power source as set forth in claim 6 wherein a region
adjacent an inner surface of one of the holes comprises an n type
region and a region adjacent an inner surface of another one of the
holes comprises an p type region.
8. The power source as set forth in claim 5 wherein the at least
one source of radiation is disposed in at least a portion of each
of the holes.
9. The power source as set forth in claim 1 further comprising a
substrate supporting the structure.
10. A method of making a power source the method comprising:
depositing an intrinsic layer on one of an n type layer and a p
type layer; depositing the other one of the n type layer and the p
type layer on the deposited intrinsic layer; and disposing at least
one source of radiation on at least the deposited one of the n type
layer and the p type layer.
11. The method as set forth in claim 10 wherein the at least one
source of radiation is at least one of an alpha particle emitter
and a beta particle emitter.
12. The method as set forth in claim 10 further comprising: forming
at least one hole that extends at least partially into the
structure; and forming a first conductive contact on the inner
surface of the hole.
13. The method as set forth in claim 12 wherein the forming at
least one hole further comprises forming the at least one hole to
extend substantially through the structure.
14. The method as set forth in claim 12 further comprising: forming
another hole that extends at least partially into the structure;
and forming a second conductive contact on the inner surface of the
another hole.
15. The method as set forth in claim 14 wherein the forming at
least one hole further comprises forming the at least one hole to
extend substantially through the structure and wherein the forming
another hole further comprises forming the another hole to extend
substantially through the structure.
16. The method as set forth in claim 14 wherein a region adjacent
an inner surface of one of the holes comprises an n type region and
a region adjacent an inner surface of another one of the holes
comprises an p type region.
17. The method as set forth in claim 14 wherein the disposing at
least one source of radiation further comprises disposing the at
least one source of radiation in at least a portion of each of the
holes.
18. The method as set forth in claim 10 further comprising
providing a substrate that supports the structure.
19. A method of generating power, the method comprising comprising:
emitting radiation into a structure comprising one or more p type
layers, one or more n type layers, and one or more intrinsic
layers, wherein each of the p type layers is separated from each of
the n type layers by one of the intrinsic layers; and converting
the emitted radiation in the structure to power.
20. The method as set forth in claim 19 wherein the emitted
radiation comprises at least one of alpha particles and beta
particles.
21. The method as set forth in claim 19 wherein the structure
further comprises: at least one hole extending at least partially
into the structure; and a first conductive contact disposed on the
inner surface of the hole.
22. The method as set forth in claim 21 wherein the at least one
hole extends substantially through the structure.
23. The method as set forth in claim 21 wherein the structure
further comprises: another hole extending at least partially into
the structure; and a second conductive contact disposed on the
inner surface of the another hole.
24. The method as set forth in claim 23 wherein the at least one
hole and the another hole each extend substantially through the
structure.
25. The method as set forth in claim 23 wherein the structure
further comprises a region adjacent an inner surface of one of the
holes that comprises an n type region and a region adjacent an
inner surface of another one of the holes comprises an p type
region.
26. The method as set forth in claim 23 wherein the structure
further comprises having at least one source of radiation of the
emitted radiation disposed in at least a portion of each of the
holes.
27. The method as set forth in claim 19 wherein the structure
further comprises a substrate supporting the structure.
Description
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/587,364 filed Jul. 13, 2004, which
is herein incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention generally relates to batteries and,
more particularly, to radio isotope batteries and methods
thereof.
BACKGROUND
[0003] The concept of an alpha voltaic battery was proposed in 1954
as disclosed in W. G. Pfann and W. van Roosbroeck, Journal of
Applied Physics, Volume 25, No. 11, pp. 1422-1434, November 1954,
which is herein incorporated by reference. A radioactive substance
that emits energetic alpha particles is coupled to a semiconductor
p/n junction diode. As the alpha particles penetrate into the p/n
junction, they decelerate and give up their energy as electron-hole
pairs. These electron-hole pairs are collected by the p/n junction
and converted into useful electricity, much like a solar cell.
[0004] The main reason alpha-voltaics and also beta-voltaics are
not commercially successful is that the alpha or beta particles
damage the semiconductor material as disclosed in G. C. Rybicki, C.
V. Aburto, R. Uribe, Proceedings of the 25.sup.th IEEE Photovoltaic
Specialists Conference, pp. 93-96, 1996, which is herein
incorporated by reference. More specifically, the pn-junction in
the alpha or beta voltaic device, which converts the alpha or beta
particle radiation, respectively, from the radioactive isotope into
electricity, rapidly degrades due to radiation damage rendering the
alpha or beta voltaic device useless long before the radioisotope
is depleted.
SUMMARY
[0005] A power source in accordance with embodiments of the present
invention comprises a structure comprising one or more p type
layers, one or more n type layers, and one or more intrinsic layers
and at least one source of radiation is disposed on at least a
portion of the structure. Each of the p type layers is separated
from each of the n type layers by one of the intrinsic layers.
[0006] A method of making a power source in accordance with
embodiments of the present invention includes depositing an
intrinsic layer on one of an n type layer and a p type layer,
depositing the other one of the n type layer and the p type layer
on the deposited intrinsic layer, and disposing at least one source
of radiation on at least the deposited one of the n type layer and
the p type layer.
[0007] A method of generating power in accordance with embodiments
of the present invention includes emitting radiation into a
structure comprising one or more p type layers, one or more n type
layers, and one or more intrinsic layers and converting the emitted
radiation in the structure to power. In the structure each of the p
type layers is separated from each of the n type layers by one of
the intrinsic layers.
[0008] The present invention provides a radio isotope battery whose
performance does not degrade in a matter of hours because of damage
to the semiconductor material from the alpha or beta particles. The
degradation is prevented in the present invention by using a
structure comprising one or more p type layers, one or more n type
layers, and one or more intrinsic layers, where each of the p type
layers is separated from each of the n type layers by one of the
intrinsic layers. The intrinsic layers prevent alpha or beta
particles from the alpha or beta particle emitter from damaging the
p type layers and the n type layers while successfully converting
energy from the alpha or beta particles into electron-hole pairs
for collection.
[0009] Another advantage of the present invention is that the radio
isotope battery can be made extremely small and thus is well suited
for emerging micro and nano applications and technologies, such as
micro electrical mechanical systems (MEMS). The radio isotope
battery can produce power on the order of micro-Watts, sufficient
for many MEMS applications. Additionally, the radio isotope battery
is very suitable for integration directly on a semiconductor device
for a "battery-on-a-chip" concept. At this time, small long lived
power sources simply do not exist for these types of applications
and systems.
[0010] Yet another advantage of the present invention is that the
radio isotope battery can be combined in parallel and series
combinations to address a wide variety of higher current, voltage,
and power requirements. For example, the present invention can be
scaled to higher power levels on the order of hundreds of watts
making it suitable for a variety of other applications, such as
deep space missions. The radio isotope battery has two unique
properties when compared to a conventional chemical battery that
make it an outstanding candidate for deep space missions. First,
the alpha or beta emitting materials have half-lives ranging from
months to hundreds of years, so there is the potential for an
almost "everlasting" batteries. Second, radio isotope batteries can
operate over a tremendous temperature range, while an ordinary
chemical batteries all fail at temperatures below -40.degree.
C.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic diagram of a radio isotope battery in
accordance with embodiments of the present invention; and
[0012] FIG. 2 is a diagram of real-space energy of an n-i-p-i
crystal.
DETAILED DESCRIPTION
[0013] A battery 10 in accordance with embodiments of the present
invention is illustrated in FIG. 1. The battery 10 includes a
substrate 12, a semiconductor structure 14 with n type layers "n"
or 16(1)-16(3), p type layers "p" or 18(1)-18(2), and intrinsic
layers "i" or 20(1)-20(4), a pair of openings or holes 22(1)-22(2),
a pair of conductive contacts 24(1)-24(2), and an alpha particle
emitter 26, although the battery 10 can comprise other numbers and
types of components, such as a beta particle or other radio isotope
emitter, in other configurations. The present invention provides a
number of advantages including providing a radio isotope battery 10
whose performance does not degrade in a matter of hours because of
damage to the semiconductor material from the emitted alpha or beta
particles.
[0014] Referring to FIG. 1, the structure 14 is formed on the
substrate 12 which is made of an amorphous silicon, although the
substrate 12 can be made of other types of semi-insulating and
insulating materials.
[0015] The structure 14 is formed on the substrate 12 and comprises
the n type layers 16(1)-16(3), p type layers 18(1)-18(2), and
intrinsic layers 20(1)-20(4), where each of the p type layers
18(1)-18(2) is separated from each of the n type layers 16(1)-16(3)
by one of the intrinsic layers 20(1)-20(4), although the structure
14 can comprise other numbers and types of layers in other
configurations. By way of example only, semiconductor materials
which could be used for the n type layers 16(l)-16(3), p type
layers 18(1)-18(2), and intrinsic layers 20(1)-20(4) include GaAs,
GaInP, SiC, Si, or other III-V, II-VI or group IV semiconductors,
although other types of materials can be used. In this example, the
semiconducting materials are grown epitaxially on single crystal
wafers, such as GaAs.
[0016] This structure 14 is used to convert the alpha radiation
from the alpha particle emitter 26 into usable electricity,
although the structure could convert other types of radio isotopes
into energy, such as beta particles. This configuration of the
structure 14 with each of the p type layers 18(1)-18(2) separated
from each of the n type layers 16(1)-16(3) by one of the intrinsic
layers 20(1)-20(4) also substantially prevents electrical
degradation of the battery 10 by minimizing the effects alpha
particle damage, although the configuration of the structure 14 can
also protect from damage from other types of radio isotopes, such
as beta particles. In this particular embodiment, each of the
intrinsic layers 20(1)-20(4) has thickness of about 5000 angstrom
which protects the n type layers 16(1)-16(3) and the p type layers
18(1)-18(2) from degradation, although each of the intrinsic layers
20(1)-20(4) could have other thicknesses which are sufficient to
prevent substantial degradation while allowing conversion of the
collected electron-hole pairs into useful electricity. By way of
example only, a diagram of the real-space energy of another
structure with this alternating configuration of an n type layer,
an intrinsic layer, a p type layer, and an intrinsic layer, i.e. an
"n-i-p-i" configuration or crystal, in accordance with other
embodiments of the present invention is illustrated in FIG. 2.
[0017] Referring back to FIG. 1, each of the holes 22(1) and 22(2)
has a cone-shape and extends in from a surface 28 of the n type
layer 16(1) of the structure 14 through all of the n type layers
16(1)-16(3), p type layers 18(1)-18(2), and intrinsic layers
20(1)-20(4) to the substrate 12, although other numbers, shapes and
configurations can be used for the holes 22(1) and 22(2) and the
holes 22(1) and 22(2) can extend through other numbers of layers in
the structure 14.
[0018] A region 30(1) adjacent an inner surface of the hole 22(1)
shown by the dashed lines in FIG. 1 is doped to form an n+ region
and a region 30(2) adjacent an inner surface of the other hole
22(2) also shown by the dashed lines in FIG. 1 is doped to form a
p+ region, although the regions 30(1) and 30(2) around the inner
surface of each of the holes 22(1) and 22(2) can have other
configurations and can be doped in different manners.
[0019] The conductive contact 24(1) is located on the inner surface
of the hole 22(1) adjacent the n+ region 30(1) and extends out from
the hole 22(1) on to a portion of the surface 28 of the n type
layer 16(1), although the conductive contact 24(1) can be formed in
other manners and in other configurations. Similarly, the
conductive contact 24(2) is located on the inner surface of the
hole 22(2) adjacent the p+ region 30(2) and extends out from the
hole 22(2) on to a portion of the surface 28 of the n type layer
16(1), although the conductive contact 24(2) also can be formed in
other manners and in other configurations. In this example,
ordinary metallization is used for each of the conductive contacts
24(1) and 24(2), although other types of conductive materials can
be used. A load 32 can coupled across the conductive contacts 24(1)
and 24(2) and to ground to store or use the generated electricity,
although the load 32 can be coupled in other manners.
[0020] The alpha particle emitter 26 is electrochemically deposited
on a portion of the n type layer 16(1) of the structure 14 and on
an inside surface of the conductive contacts 24(1) and 24(2) in the
holes 22(1) and 22(2), although the alpha particle emitter 26 can
be deposited or placed in other manners and configurations and
other types of radio isotope emitters can be used, such as a beta
particle emitter. In this particular embodiment, the alpha particle
emitter 26 is Am-241 thermally diffused in silver foil and
over-coated with a thin metal layer, which is the same materials
found in household smoke detectors, although other types of
radiation sources could be used.
[0021] A method of making a battery in accordance with embodiments
of the present invention will be described with reference to FIG.
1. The substrate 12 is made of an amorphous silicon is provided,
although other types of substrates can be used. In this particular
embodiment: the n type layer 16(3) is deposited on a surface of the
substrate 12; the intrinsic layer 20(4) is deposited on a surface
of the n type layer 16(3); the p type layer 18(2) is deposited on a
surface of the intrinsic layer 20(4); the intrinsic layer 20(3) is
deposited on a surface of the p type layer 18(2); the n type layer
16(2) is deposited on a surface of the intrinsic layer 20(3); the
intrinsic layer 20(2) is deposited on a surface of the n type layer
16(2); the p type layer 18(1) is deposited on a surface of a
surface of the intrinsic layer 20(2); the intrinsic layer 20(1) is
deposited on a surface of the p type layer 18(1); and the n type
layer 16(1) is deposited on a surface of the intrinsic layer 20(1)
to form the structure 14, although the structure 14 can comprise
other numbers and types of layers in other configurations. By way
of example only, in this particular embodiment the n type layers
16(l)-16(3) are each about 500 angstroms thick, each of the p type
layers 18(1)-18(2) is about 500 angstroms thick, and each of the
intrinsic layers 20(1)-20(4) is about 5000 angstroms thick,
although these thicknesses can vary based on the particular
application.
[0022] In this particular embodiment, conventional photolithography
is used to etch the cone-shaped holes 22(1) and 22(2) into the
structure 14 through all of the n type layers 16(1)-16(3), p type
layers 18(1)-18(2), and intrinsic layers 20(1)-20(4) to the
substrate 12, although other numbers, shapes and configurations can
be used for the holes 22(1) and 22(2) and the holes 22(1) and 22(2)
can extend through other numbers of layers in the structure 14. The
region 30(1) adjacent the inner surface of the hole 22(1) is doped
to form an n+ region and the region 30(2) adjacent the inner
surface of the other hole 22(2) is doped to form a p+ region,
although the regions 30(1) and 30(2) around the inner surface of
each of the holes 22(1) and 22(2) can have other configurations and
can be doped in different manners.
[0023] A conductive material is deposited on the surface 28 of the
n type layer 16 and on the inner surfaces of the holes 22(1) and
22(2) and portions of the conductive material on the surface 28 of
the n type layer 16 are etched away to form the conductive contacts
24(1) and 24(2), although other numbers and types of conductive
contacts and other manners for forming the conductive contacts can
be used. In this particular embodiment, ordinary metallizations are
used for form the conductive contacts 24(1) and 24(2). A load 32
can be coupled to each of the conductive contacts 24(1) and 24(2)
and to ground, although the load 32 can be coupled in other
manners.
[0024] The alpha particle emitter 26 deposited on a portion of the
surface 28 of the n type layer 16(1) of the structure 14 and on an
inside surface of the conductive contacts 24(1) and 24(2) in the
holes 22(1) and 22(2), although the alpha particle emitter 26 can
be deposited in other manners and configurations and other types of
radio isotope emitters, such as a beta particle emitter can be
used. In this particular embodiment, the alpha particle emitting
isotopes for the alpha particle emitter 26 are electrochemically
deposited, although other manners for forming the alpha particle
emitter 26 or other radio isotope emitter can be used, such as by
physically placing the alpha particle emitter 26 on the structure
14.
[0025] The operation of the battery 10 in accordance with
embodiments of the present invention will now be described with
reference to FIG. 1. Alpha particles are emitted from the alpha
particle emitter 26 into the structure 14, although other types of
radio isotopes could be emitted, such as beta particles. As the
alpha particles from the alpha particle emitter penetrate into the
"p-i-n" junctions formed by each of the p type layers 18(1)-18(2)
separated from each of the n type layers 16(1)-16(3) by one of the
intrinsic layers 20(1)-20(4), they decelerate and give up their
energy by creating electron-hole pairs in the structure 14. These
electron-hole pairs at each of the "p-i-n" junctions formed by each
of the p type layers 18(1)-18(2) separated from each of the n type
layers 16(1)-16(3) by one of the intrinsic layers 20(1)-20(4) are
converted into useful electricity much like a solar cell.
[0026] The electron and holes are collected in the spatially
separated n type layers 16(1)-16(3) and p type layers 18(1)-18(2)
of the structure 12 and are transported in a parallel direction to
the conductive contacts 24(1) and 24(2). The n+ region 30(1) and
the p+ region 30(2) provide a lateral field or extraction voltage
within the collection layers. As a result, charge separation and
transport occur within two separate orthogonal planes so that there
is a reduction in the overlap of the electron and hole wave
functions and hence longer recombination lifetimes. The battery 10
is not diffusion limited, but instead is drift dominated.
Therefore, the battery 10 has a high radiation tolerance because of
the "p-i-n" junctions formed by each of the p type layers
18(1)-18(2) separated from each of the n type layers 16(1)-16(3) by
one of the intrinsic layers 20(l)-20(4), but still recovers energy
from the alpha particle radiation from the alpha particle emitter
26 or the energy from other types of emitted radio isotopes. This
generated electricity or power is transferred to a load 32 which is
coupled to the conductive contacts 24(1) and 24(2) and is also
coupled to ground.
[0027] Accordingly, the present invention provides a radio isotope
battery whose performance does not degrade in a matter of hours
because of damage to the semiconductor material from the alpha
particles. Additionally, the present invention provides a radio
isotope battery that can be made extremely small and thus is well
suited for emerging micro and nano applications and technologies,
such as MEMS. Further, the present invention is very suitable for
integration directly on a semiconductor device for a
"battery-on-a-chip" concept. The present invention also can be
combined in parallel and series combinations to address a wide
variety of higher current, voltage, and power requirements.
[0028] Having thus described the basic concept of the invention, it
will be rather apparent to those skilled in the art that the
foregoing detailed disclosure is intended to be presented by way of
example only, and is not limiting. Various alterations,
improvements, and modifications will occur and are intended to
those skilled in the art, though not expressly stated herein. These
alterations, improvements, and modifications are intended to be
suggested hereby, and are within the spirit and scope of the
invention. Additionally, the recited order of processing elements
or sequences, or the use of numbers, letters, or other designations
therefore, is not intended to limit the claimed processes to any
order except as may be specified in the claims. Accordingly, the
invention is limited only by the following claims and equivalents
thereto.
* * * * *